Pyridyltetrahydropyridine derivatives and pyridylpiperidine derivatives are useful in the fields of drugs, agricultural chemicals, catalyst ligands, combinatorial chemistry, organic electroluminescent devices, charge transferors, electrophotographic photoreceptors, dyes and so on, and various types of those derivatives are developed already in the medicinal field in particular. For instance, the pyridyltetrahydropyridine derivatives hitherto disclosed are α1A receptor antagonists (See Patent Document 1 and Patent Document 2; the cited documents are shown hereinafter), 5-HT1A receptor antagonists (See Patent Document 3), tetrabenazine antagonists (See Non-patent Document 1), TNP inhibition activators (See Patent Document 4), neurodegenerative disease fighting drugs (See Patent Document 5), and so on. And the pyridylpiperidine derivatives hitherto disclosed are, e.g., neuropeptide Y or Y5 antagonists (See Patent Document 6 and Patent Document 7), corticotropin-releasing factor inhibitors (See Patent document 8), α1A adrenoreceptor antagonists (See Patent Document 9) and metalloprotease inhibitors (See Patent Document 10 and Patent Document 11).
On the other hand, methods of reducing bipyridines directly to pyridyltetrahydropyridine derivatives or pyridylpiperidine derivatives have not been developed yet, but these derivatives required multiple-step syntheses.
The synthesis method according to dehydration reaction of piperidinol (See Patent Document 12) is disclosed as one example of manufacturing methods of tetrahydropyridine derivatives. However, such a method has a problem in industrial-scale production since a piperidinol analogue used as the starting material is generally hard to get.

As another method, it is known that tetrahydropyridine derivatives can be synthesized by nucleophilic substitution using halogenated pyridines (See Patent Document 13). However, this synthesis requires the use of a highly toxic material, such as tributyl stannane, or a highly reactive raw material such as an organolithium compound or a Grignard compound, so it also has a problem in industrial-scale production.
Further, there is known the method of manufacturing pyridylpiperidines directly from bipyridines with the aid of nickel-aluminum alloy (See Non-patent Document 2). However, such a method requires a long reaction time of 385 hours, so a problem lies in the industrialization thereof.

Additionally, there are known some methods for production of pyridylpiperidines from bipyridines through selective reduction of one aromatic ring alone in each bipyridine. In an example of such methods, bipyridine derivatives are oxidized by use of peroxybenzoic acid to be guided to N-oxides, and then undergo hydrogenation reaction using 10% palladium carbon as a reduction catalyst. However, such a production method requires a peroxide compound like peroxybenzoic acid, so it is difficult to enlarge the reaction scale (See Non-patent Document 3).
    Patent Document 1: WO 99/07695    Patent Document 2: U.S. Pat. No. 6,159,990    Patent Document 3: WO 99/03847    Patent Document 4: WO 01/29026    Patent Document 5: WO 02/42305    Patent Document 6: WO 01/85714    Patent Document 7: WO 99/48888    Patent Document 8: U.S. Pat. No. 6,107,301    Patent Document 9: U.S. Pat. No. 6,316,437    Patent Document 10: WO 01/62742    Patent Document 11: WO 02/74767    Patent Document 12: JP-T-2003-512370    Patent Document 13: JP-T-11-506118    Non-patent Document 1: Walfred S. Saari, The Journal of Medicinal Chemistry, (America), The American Chemical Society, 1984, pp. 1182-1185    Non-patent Document 2: George Lunn, The Journal of Organic Chemistry, (America), The American Chemical Society, 1992, pp. 6317-6320    Non-patent Document 3: Jean-Christophe Plaquevent & Ilhame Chichaoui, Bulletin de la Societe Chimique de France, (France), Societe Chimique de France, 1996, pp.